Glaucoma refers collectively to a group of eye diseases whose molecular basis is poorly understood. Worldwide primary open angle glaucoma (POAG) is one of the leading causes of blindness and is currently incurable. Distinguishing symptoms of POAG are increased intraocular pressure (IOP) and glaucomatous optic neuropathy. Increased resistance to aqueous outflow through the filtering trabecular meshwork (TM) tissue appears to play a key role in the onset and progression of POAG. Blockage at the level of trabecular meshwork leads to increased IOP. Proteomic and Western analyses of normal and glaucomatous TM have revealed cochlin, a secreted protein with unknown function, present exclusively in glaucomatous but not in normal TM. Subsequently we have also observed cochlin containing deposits by immunohistochemistry in glaucomatous TM. In the human cochlea, cochlin is associated with mucopolysaccharide deposits in progressive auditory dysfunction. In the TM, deposition of cochlin and mucopolysaccharides may interfere with regulation of aqueous outflow and may cause slow but progressive elevation of IOP. We have extended these studies to mice and found that cochlin levels were elevated in the DBA/2J model of glaucoma but not in control animals. The studies proposed here will use mouse models to determine the role of cochlin in IOP elevation. The central hypothesis to be tested is that cochlin deposits in the extracellular matrix obstruct aqueous outflow in glaucomatous TM, elevate IOP and contribute to the pathogenesis of POAG. The long- term goals of this project are to establish the mechanistic involvement of cochlin in IOP elevation and the pathogenesis of POAG, and to develop effective therapies for preventing disease progression. Our hypothesis will be tested with following specific aims: (1) To determine whether cochlin over-expression results in elevated IOP;(2) To determine whether DBA/2J mice lacking cochlin maintain normal IOP;(3) To test whether cochlin message down-regulation results in normal IOP in DBA/2J mouse. Methods will include intraocular injections, IOP measurements, viral infections, immunohistochemisty as well as other molecular and cell biological techniques.